More than 1.8 million people in those groups are the intended focus of new annual satisfaction surveys unveiled yesterday as part of a broader citywide initiative to grade its 1,450 schools and improve the system.

The multiple-choice questionnaires were to begin arriving at schools and homes yesterday in eye-catching bright-green envelopes that city officials said they hoped would grab the attention of parents and spur them to participate.

Surveys will be given to middle- and high-school students in classes. Elementary-school students will not take part.

Parents and teachers must return the surveys to their schools by May 18.

The anonymous questionnaires touch on general themes of school safety, student engagement and quality of instruction, but are tailored to each audience.

For instance, students are asked whether they feel safe at school, whereas teachers are asked whether they feel supported by their principal and colleagues. Parents are asked how often they are invited to sit in on a lesson.

They run between 42 and 73 questions, depending on the group being surveyed, and take about 20 minutes to complete.

In announcing the release of the voluntary surveys, Mayor Bloomberg described the unprecedented, $2 million effort as second in scope only to the national census, and took pains to divert skepticism about how seriously responses will be taken.

“Every parent’s voice will count, every teacher’s voice will count and the voices of our students will count,” Bloomberg said at PS 76 in The Bronx. “These are not ordinary surveys. They won’t be stuffed in a collection box or left to collect dust in a corner.”

The results will help the city Department of Education to determine a letter grade from A to F for each school by September.

The so-called “Learning Environment Surveys” will count for about 10 percent of the grading scheme, officials said, with the rest of the letter grade relying primarily on a more sophisticated analysis of standardized test scores.

Despite the relatively low weighted value of the surveys within the $25 million grading initiative, Schools Chancellor Joel Klein suggested their input was imperative.

“We’re going to learn for the first time in a systematic, highly coordinated way how our schools are doing and what they need to improve,” he said.

“I think it’s a good idea,” said PS 76 parent Erica Rodriguez, who picked up her 6-year-old kindergarten son yesterday. “It’s important for [the city] to know what the parents think of their schools.”

Not all parents were crowing about the survey.

A small contingent who participated in focus groups for the survey earlier this year said the end result gave short shrift to some of their most pressing concerns, including class sizes and school-parent leadership, and are calling for a boycott.

“This is what we’re going to get the first time around,” said Marvin Shelton, president of the Community Education Council in District 10 in The Bronx. “But I think people should fill it out as honestly as they can. Next time we’ll sit down and see if we can add questions we feel are missing.”